1. Field of the Invention
The present invention relates to an electron emission display including a spacer and, more particularly, to an electron emission display that areas of spacers per unit areas in contact with a panel of the electron emission display are varied in at least one direction from a central region to a periphery region.
2. Discussion of Related Art
In general, an electron emission device uses a hot cathode or a cold cathode as an electron source. The electron emission device using the cold cathode may be of a field emitter array (FEA) type, a surface conduction emitter (SCE) type, a metal-insulator-metal (MIM) type, a metal-insulator-semiconductor (MIS) type, a ballistic electron surface emitting (BSE) type, and so on.
Using these electron emission devices, an electron emission display, various backlights, an electron beam apparatus for lithography, and so on can be implemented. An electron emission display includes a cathode substrate including an electron emission device to emit electrons, and an anode substrate for allowing the electrons to collide with a fluorescent layer to emit light. Generally, in an electron emission display, the cathode substrate is configured as a matrix, such that cathode electrodes and gate electrodes intersect each other, and includes a plurality of electron emission devices defined in the intersected regions, and the anode substrate includes fluorescent layers emitting light by the electrons emitted from the electron emission devices and anode electrodes connected to the fluorescent layers. The electron emission display is configured to drive the intersection regions in a matrix manner to selectively display the intersection regions. The cathode substrate and the anode substrate interpose a spacer therebetween in order to maintain a certain gap. The spacer functions to prevent the electron emission device and the anode substrate from being deformed and damaged due to a pressure difference between inner and outer parts when a space between the electron emission device and the anode substrate is vacuum-packaged, and to reduce non-uniformity of brightness based on emission positions by uniformly maintaining the gap between the two substrates.
An example of the electron emission display adapting the aforementioned spacer is disclosed in Korean Patent Laid-open Publication No. 2003-31355.
FIG. 1 is a cross-sectional view of an electron emission display including a conventional spacer. The electron emission display includes an electron emission device 10, an anode substrate 20, line-shaped cathode electrodes 12 provided at a surface of the electron emission device 10, line-shaped gate electrodes 16 perpendicularly intersecting the cathode electrodes 12 and interposing insulating layers 14 therebetween, a line-shaped anode electrode 22 provided at a surface of the anode substrate in the same direction as the cathode electrodes 12. A plurality of openings in the gate electrodes 16 and the insulating layers 14 are formed at pixel regions, at which the cathode electrodes 12 and the gate electrodes 16 intersect each other. Also included are electron emission parts 18 made of a carbon-based material such as carbon nanotube (CNT) and so on are provided at the cathode electrodes 12 in the respective openings. Fluorescent layers 24 emitting light when electrons emitted from the electron emission parts 18 collide therewith are provided at a surface of the anode electrode 22 at positions opposite to the electron emission parts 18. One end of the spacer 26 for supporting both vacuum-sealed substrates 10 and 20 is supported at the surface of the anode electrode 22 between the fluorescent layers 24, and the other end of the spacer 26 is supported at the gate electrode 16.
In the case of a display panel adapting the spacers, in general, spacers having the same shape are adapted under the condition that stress applied to the panel is uniform. However, since the stresses applied to the panel are different from each other based on its regions in spite of adaptation of the spacer, it is difficult to thoroughly suppress deformation of the substrate and to maintain uniformity of color reproduction due to brightness differences.